Hello everyone,

I have been racking my mind with this issue and am coming to you for help. I have an XK150 S, which still is wired with a positive earth and two 6V batteries. The issue I am having is that I know that on the right side, the terminal nearest to the front is supposed to be negative and the terminal towards the rear should be positive (earth). However, on the left side, I stupidly took the battery out without confirming that the terminal arrangement was the same, and since the battery terminals are on diagonal corners, I cannot confirm what the positioning was before I took it out. I would trace the wires back to see which is negative and which is earth, however I am not with the car at the moment so I cannot examine more thoroughly at this time. I do know that when I put the left side battery in the car, I hooked the wire towards the back into the positive (earth) battery terminal and the wire towards the front into the negative battery terminal. I am still waiting to receive the passengers side battery, but with the right side battery removed, the positive wire touched some bare metal and I had large sparks. Do any of you know whether (on a car with original wiring) the left side battery was positioned with the negative terminal towards the front or the back?

Here's the series of events in simpler terms:
1. confirmed that RIGHT side battery was negative terminal towards front, positive (earth) towards rear
2. removed both batteries
3. put new battery into LEFT side, with negative terminal towards front and positive towards rear
4. on right side, when the POSITIVE wire was touched to bare metal, large sparks appeared

Based on this, does anyone have an idea as to whether the left side battery should be negative terminal towards front or vise versa? I am thinking that positive should be towards front on the left, but please correct me if I am wrong.